Tom Lane <t...@sss.pgh.pa.us> wrote: > The reason we haven't done it is that it looks like the SQL > standard requires type resolution for set-ops to happen one pair > of input relations at a time. Well, it also requires that an unadorned quoted literal is of type char(n). This is inextricably tied in with the PostgreSQL deviation from standard handling of literals so that user-defined types can be more gracefully handled. >From my perspective the "right" answer is to be able to resolve two unknown types to unknown rather than text in a few places where we are currently compelled to assign a concrete type. This just seems odd and wrong: test=# select pg_typeof((select '1' limit '1')); pg_typeof ----------- unknown (1 row)
test=# select pg_typeof((select '2' limit '1')); pg_typeof ----------- unknown (1 row) test=# select pg_typeof((select '1' union all select '2' limit '1')); pg_typeof ----------- text (1 row) Likewise with the CASE predicate and it abbreviated forms (e.g., COALESCE). I remember looking at this a couple years ago and finding that making that work was more time than I could throw at it just then, but I'm convinced that several warts on the type handling which generate posts on this list now and again would best be dealt with that way. At least part of the previous discussion was on the thread which starts here: http://archives.postgresql.org/pgsql-hackers/2009-09/msg00388.php As I recall, one issue is that as the code is currently organized, some of this type resolution would need to be deferred to execution time. :-( -Kevin -- Sent via pgsql-bugs mailing list (pgsql-bugs@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-bugs
